

Since each Gaussian component in (REF ) shares the same variances \(v^{\nu }_{i,m^{\prime }+1}\) , we cluster the mean values into \(V\)  groups and approximate the values of each group as one mean value. Clustering algorithms, such as K-means [1]} and expectation maximization (EM) [2]}, can be used for this purpose.
In this work, we group the mean values \(\lbrace \hat{\nu }_{i,m^{\prime }+1,l,q}\rbrace \)  as follows.
